Mosquitoes from container habitats are important vectors of human viral diseases, including several forms of encephalitis, Dengue, and Chikungunya. Controlling these diseases remains dependent on controlling mosquito populations, which is fundamentally the practical application of population dynamic theory. Whether mosquito control depends on chemical control, biological or biorational control, or novel application of transgenic methods, control efforts directed at larvae can impact density dependent effects on mosquito survival, growth, and development rate. When extrinsic mortality reduces density, the population may produce as many or more adults, or equal or greater population growth, if that reduced density ameliorates the negative effects of density. Though these possibilities of compensatory or overcompensatory mortality have been the subject of theory and discussion in the context of mosquito control, we still have very little empirical information about the forms of density dependence acting on different mosquitoes in nature, the effects of timing, extent, and source of mortality on production of adults, and ultimately the likelihood of compensation or overcompensation under different circumstances in nature. Control efforts that seek to impose extrinsic mortality will be more effective if that extrinsic mortality is applied at the right time and at the right level. Thus our basic understanding of the population ecology of density dependence and the conditions that lead to compensation will likely enable mosquito control efforts to be successful and more efficient. The research proposed here will address the questions: 1. What is the form of density dependence within populations of five major container-dwelling vectors of arboviruses in North America, focusing on how the shape of the relationship between estimated per capita growth and density varies among species. 2. Does the likelihood of compensation depend, for each of these species, on the timing and extent of mortality imposed on the larvae? 3. What is the likelihood of both density dependence and of compensatory mortality in different mosquito species in a natural field setting? 4. Is it equally likely that extrinsic mortality imposed by a natural enemy (the predator Toxorhynchites rutilus) or by the bacterial toxin from Bacillus thuringiensis israelensis (Bti) could result in compensatory mortality? The proposed research will generate considerable new knowledge about density dependence in populations of mosquitoes, some of which may be very useful for mosquito control of the focal mosquito species. Beyond the focal species under study, the approach used in this research is likely to serve as a model for additional studies of density dependence and compensation in other disease vectors.